Imaging Neural Mechanisms Underlying Pain Modulation

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Bethesda,
Maryland20892

Purpose:

This study will evaluate brain pathways involved in feeling pain and pain relief following
administration of pain medication. Magnetic resonance imaging (MRI) will be used to measure
brain activity at sites that become more active following oral surgery and then to see if
the activity changes after pain medication is administered. MRI combines a powerful magnet
with an advanced computer system and radio waves to produce detailed pictures of organs and
tissues. During the scan, the subject lies on a table in a narrow cylinder containing a
magnetic field. He or she can speak with a staff member via an intercom system at all times
during the procedure.
Healthy dental patients recruited through the NIH Clinical Research Volunteer Program may
enroll in this study. Participants will undergo the following tests and procedures in two
clinic visits:
Visit 1 - Sensitivity Testing
Participants are tested for sensitivity to warm and hot temperatures. A probe is applied to
the skin (usually the forearm) and heated to temperatures ranging from room temperature to
that of a hot cup of coffee. Participants rate the temperature using a scale ranging from
"no pain" to the "worst pain imaginable" and rate the unpleasantness of the heat using a
similar scale. The probe is applied up to 30 times, using random heat intensities.
Participants are also asked compare the heat intensity to varying levels of sounds and to
rate the magnitude of different sensations they have experienced in the past, such as the
brightness of the sun and the loudness of a jet plane. A blood sample of about 2 ounces is
also collected at this visit for DNA analysis to look for genes related to pain.
Visit 2 - Oral Surgery
Under local anesthetic, participants undergo extraction of their lower right wisdom tooth.
After surgery, the patient is moved to the MRI scanner for brain imaging over 1-2 hours
while the local anesthetic wears off. Patients may request a postoperative pain drug
(Toradol) during the procedure, if needed. When the scan is complete, patients are dismissed
from the clinic with additional pain medication (flurbiprofen) to use at home as directed.

Study summary:

Functional neuroimaging provides a powerful tool for understanding how the brain may be
involved in the perception of pain. It has made it possible to identify areas of the brain
that are involved in the perception of experimental pain but very few studies have evaluated
the sites in the brain that are activated during clinical pain and the effects of analgesic
drugs. The proposed study will use the surgical removal of an impacted third molar as a
model of acute clinical pain to identify sites that are activated following the offset of
local anesthesia and to examine the effects of the NSAID analgesic ketorolac on attenuating
sites that are activated as pain is relieved. Scans will be performed under non-pain
baseline conditions, and again immediately following surgery as the local anesthetic wears
off, clinical pain occurs, and following administration of the NSAID ketorolac. Differences
among subjects in the amount of pain reported and brain activation will be compared to
subjects' prior ratings of experimental pain and the presence of any genetic polymorphisms
that are related to pain perception, inflammation, known pain pathways, or psychological
factors related to pain. The findings from this research may help to reveal how pain is
appreciated in the central nervous system, pharmacologically modified by NSAID analgesics
and differs among individuals due to genetic factors.

Criteria:

ELIGIBILITY CRITERIA:
Subjects will be a convenience sample selected from the pool of 500 - 700 new patients
screened annually for acute pain studies. Inclusion and Exclusion criteria will be
applied to result in a homogeneous population of subjects with respect to the surgical
difficulty of the tooth being extracted, a single lower right third molar.

NCT ID:

NCT00078364

Primary Contact:

N/A

Backup Contact:

N/A

Location Contact:

Bethesda, Maryland 20892United States

There is no listed contact information for this specific location.

Site Status: N/A

Data Source: ClinicalTrials.gov

Date Processed: June 25, 2018

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